A certain assay for serum alanine aminotrans- ferase (ALT) is rather imprecise. The results of repeated assays of a single specimen follow a normal distribution with mean equal to the true ALT concentration for that specimen and standard deviation equal to 4 U/l (see Example 2.2.12). Suppose that a certain hospital lab measures many specimens every day, performing one assay for each specimen, and that specimens with ALT readings of 40 U/l or more are flagged as "unusually high." If a patient's true ALT concentration is 35 U/l, what is the probability that his specimen will be flagged as "unusually high"?